Capgemini
Company
Numerical Ability
Algebra
How many distinct pairs of b,c are possible such that the both the equations x^2+bx+c=0 and x^2+cx+b=0 have real roots?
A.one
B.two
c.More than two
d.None
Read Solution (Total 5)
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- try (b,c)= (5,6) (7,8) (9,10)
all of these pairs satisfy b^2-4c>0 and c^2-4b>0 i.e. condition for real roots of quadratic.
Hence more than 2 pairs of b,c are possible.
option c. is correct - 7 years agoHelpfull: Yes(11) No(2)
- for the real roots, b^2-4c>0 --------(i) and c^2-4b>0------------(ii)
using these two equations we get b>4 and c>4
these will help you to choose the values of b, c
now consider b=5,c=5 then those two equation do not get satisfied, so if we take b=5 and c=6 now the equations are satisfied....similarly (b,c)= (6,7) , (7,8), (8, 9), (9, 10) etc also satisfy the equations
as we are asked about the distinct pairs of b ,c , then (5,6),(7,8),(9,10) can be considered .....so option (c)more than two holds the correct answer - 7 years agoHelpfull: Yes(5) No(1)
- please provide solution without which it seems unhelpful
- 8 years agoHelpfull: Yes(1) No(2)
- subtract the two equations
x^2+bx+c=0
x^2+cx+b=0
=> x=1 satisfies the equation
one real root - 7 years agoHelpfull: Yes(1) No(4)
- one is the ans
- 7 years agoHelpfull: Yes(0) No(1)
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